Lecture 21 : Other Emerging Infections Overview

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Lecture 21 Other Emerging Infections Overview

• NEWLY RECOGNISED INFECTIOUS DISEASES
• Known slow burners
• Heart diseases
• Peptic ulcer
• Cancers
• Other diseases
• DELIBERATELY CAUSED INFECTIOUS DISEASES

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Newly Recognised Infections

• The term is used to describe diseases
  traditionally thought to be degenerative (i.e.
  non-infectious), but now thought to be caused by
  a biological agent (e.g. bacteria, virus).
• Not necessarily on the increase it is the
  causes that are emerging.

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Slow Burners

• Some infectious diseases are known to be slow
  burners (i.e. long incubation period).
• Chicken pox is caused by the varicella zoster
  virus, which then becomes dormant, but may cause
  shingles in later life.
• Mycobaterium tuberculosis can hide within the
  immune system, but break out if the immune system
  becomes compromised to cause active tuberculosis.
• Creutzfeld-Jacob disease (CJD) was long thought
  to be degenerative, but is now known to be caused
  by a prion.

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Heart Diseases

• Streptoccous pyrogenes causes scarlet fever in
  childhood (now much milder than in the past), but
  it can develop into rheumatic fever, which in
  turn may result in rheumatic heart disease.
• Trypanosoma cruzi causes Chagas disease, which
  is the leading cause of heart disease in Latin
  America.
• Chlamydia pneumoniae is a suspected factor in
  atheroma, hypertension and corononary heart
  disease.
• Porphyromonas gingivalis is also a suspect.

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Cancers and Ulcers

• Helicobacter pylori is now a known cause of
  peptic ulcers.
• Also suspected cause of gastric cancer.
• Infections are suspected in other cancers
• Liver (hepatitis B virus)
• Cervix (human papilloma virus)
• Anus, vagina, penis, mouth and throat (human
  papilloma virus)
• Liver (Aspergillus flavus).

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Other Diseases

• Other diseases suspected of being caused by
  infections include
• Appendicitis
• Multiple sclerosis
• Leukaemia
• Type 2 diabetes
• Schizophrenia.

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Summary

• Causality is difficult to prove because
• a) Long latency period
• b) Agent does not always produce the disease
• c) Agent is not the only cause of the disease.
• New discoveries will increase the likelihood of
  vaccines or effective therapeutic responses.

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Biological Weapons(1)

• An epidemic might be started on purpose.
• Signatories of the 1972 Biological Weapons
  Convention agreed not to develop biological
  weapons.
• Soviet Biopreparat programme employed 30,000.

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St. Petersburg
Kirov
Sergiyev Posad
Novosibirsk
Sverdlovsk
Moscow
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Biological Weapons(2)

• Russians had one of two repositories of smallpox
  samples. These are believed to have been used for
  mass production of smallpox, which may now have
  found its way to North Korea and Iran.
• Other countries believed to have biological
  weapons include Israel, Syria, Libya, Iraq,
  India, China, Taiwan, and S. Africa.
• Biggest fear is they might be used by terrorist
  groups. The US was attacked by anthrax in 2001.

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